With the need for reducing costs or times associated with business trips, more companies are moving towards transmission systems to have teleconference or videoconference among remotely located offices via a communication network such as the Internet. The transmission systems allow transmission of contents data such as image data and/or sound data among a plurality of transmission terminals that are remotely located from one another through the communication network to facilitate communication among the plurality of transmission terminals.
The recent transmission systems have a function of notifying a user at a request transmission terminal of information indicating the current state of a counterpart transmission terminal before the user at the request transmission terminal starts communicating with a user at the counterpart transmission terminal. For example, the transmission system described in U.S. Patent Application Publication No. 2007/0263075 manages user names and associated identities of potential users at transmission terminals such that the stored information regarding the potential users are constantly refreshed as users at transmission terminals log in or out. Before the user at the request transmission terminal initiates videoconference, the user at the request transmission terminal accesses a screen that lists user names and associated identities of potential users that are constantly refreshed.
While the user at the request transmission terminal is refrained from initiating videoconference with a user who is not currently logged in, the above-described technique does not provide much information other than whether the user is logged in or not. For example, even when the user at the counterpart transmission terminal is logged in, the user at the request transmission terminal may not be able to communicate with the user at the other end due to a trouble in the counterpart transmission terminal such as a trouble in microphone or speaker of the counterpart transmission terminal. In such case, the user at the counterpart transmission terminal still tries to initiate communication with the user at the other end, without knowing that the user at the other end is not available for communication.